/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package axil.stdlib.numbers.function;

import axil.api.AxilObject;
import axil.api.extend.Environment;
import axil.api.extend.Function;
import axil.api.extend.Parameters;
import axil.api.extend.Source;
import axil.stdlib.numbers.type.Int;
import axil.stdlib.numbers.type.Num;

import java.math.RoundingMode;
import java.util.HashMap;
import java.util.Map;

import static axil.framework.Functions.*;


/**
 * A function for performing rounding. Two optional arguments are supported:
 *
 * 		round(number)
 * 		round(number, digits)
 * 		round(number, digits, "mode")
 */
public class Round implements Function {
	private static final Map<String,RoundingMode> modes =
	    new HashMap<String, RoundingMode>();
	static {
		modes.put("up", RoundingMode.UP);
		modes.put("down", RoundingMode.DOWN);
		modes.put("ceiling", RoundingMode.CEILING);
		modes.put("floor", RoundingMode.FLOOR);
		modes.put("half-up", RoundingMode.HALF_UP);
		modes.put("half-down", RoundingMode.HALF_DOWN);
		modes.put("half-even", RoundingMode.HALF_EVEN);
	}


	/**
	 * Execute this function with the given arguments. The Axil compiler will
	 * ensure that the number of arguments passed to the function are valid.
	 * If this function fails during execution for any reason, then an exception
	 * is thrown.
	 */
	public AxilObject eval(Environment env, Parameters params, Source source) {
		Num value = cast(Num.class, params.a());
		Int digits = cast(Int.class, opt(params.b(), Int.zero));
		String m = opt(params.c(), string("half-up")).toString();
		RoundingMode mode = modes.get(m);
		if (mode == null) {
			throw error(axil(), "bad-rounding-mode", nv("mode", m));
		}
		return value.round(mode, digits.value());
	}
}
